The present invention relates to a controller for an internal combustion engine including a throttle valve that adjusts a cross-sectional area of an intake passage, an exhaust gas recirculation device, and a fuel injection valve that injects fuel supplied to the internal combustion engine.
Japanese Laid-Open Patent Publication No. 2000-136760 discloses an example of an internal combustion engine that includes an exhaust gas recirculation device. The exhaust gas recirculation device includes an exhaust gas recirculation passage, which connects a portion of an intake passage with an exhaust passage, the portion being located at the downstream side of the throttle valve. The exhaust gas recirculation device also includes an EGR valve (recirculation valve), which opens and closes the exhaust gas recirculation passage, and an actuator, which opens the EGR valve. The EGR valve is configured to open when moved against the pressure of the exhaust passage. The actuator opens the recirculation valve by generating force that is in accordance with the difference of the pressure of the exhaust passage and the pressure of the intake passage.
There is a known method for diagnosing an exhaust gas recirculation device that includes a recirculation valve for an abnormality from the flow rate of fluid flowing into an intake passage via an exhaust gas recirculation passage when opening a recirculation valve while executing a fuel cut-off process that stops fuel injection in an internal combustion engine. The difference of the pressure of the exhaust passage and the pressure of the intake passage is especially large during the fuel cut-off process. When an actuator opens the recirculation valve during the fuel cut-off process, the actuator requires a large force. This may result in the enlargement of the actuator.